The present invention relates generally to a traversing boom system. More particularly, the present invention relates to a traversing boom system for a forklift providing a high degree of operator visibility.
Forklifts have long been known in the construction industry and typically comprised a frame having a front and rear set of opposing wheels, an engine and drivetrain, an operator cockpit, and a load handling attachment at the end of a boom. Forklifts having a high level of maneuverability were usually preferred for the transport and placement of loads in and around construction sites. The typical construction site also required, for safe and efficient operation, that a forklift provide its operator with a high level of visibility of the terrain surrounding the forklift. Such a forklift is described in application Ser. No. 09/286,152 which is incorporated herein by reference and of which this application is a continuation-in-part. Operator visibility of the terrain surrounding a forklift was crucial to avoid injury to personnel working thereabout and to avoid damaging nearby structures, waterlines or electrical lines. When provided with a high degree of visibility of the surrounding terrain, an operator could quickly and efficiently operate the forklift with confidence it was being done safely.
Prior to transporting a load, a forklift operator would usually engage the load with the load handling attachment at the end of the boom, lift the load from the surface upon which it rested by elevating the boom, and adjust the boom and load to a transport configuration. The transport configuration positioned the load at a sufficient distance from the ground to ensure that neither the load nor the load handling attachment of the boom would inadvertently encounter the ground during transportation. The load elevation varied according to the terrain and would necessarily be greater when the terrain was rough than when the terrain was relatively even. Stability dictated, however, that the load not be positioned too far above the forklift center of gravity. Other aspects of the environment in which the forklift was used also limited the elevation of the load in the transport configuration. For example, a forklift employed to move a load from a construction site into a building might have been required to pass through a doorway. At that time, the vertical elevation of the boom, load handling attachment or load could be no higher than the vertical opening of the doorway.
Forklifts having a variable reach or extensible boom were also well known in the construction industry. An extensible boom was usually pivotally connected to the forklift""s frame, at, for example, a rearward portion thereof, and extended forward over the frame. The operator cockpit was typically mounted at the side of the frame between the front and rear wheels. The engine was often placed at the side of the frame opposing the operator cockpit or at the rear of the frame adjacent to the pivotal connection between the boom and the frame. As known to those of ordinary skill in the art, the extensible boom was employed to facilitate the handling of a load at a location to which the forklift could not travel. For example, placement or retrieval of a load on a second or higher floor of a building could require the forklift operator to elevate and extend the boom to place or retrieve the load.
Alternatively, some forklifts have mounted the boom pivot to a traversing boom carriage capable of travelling along portions of the forklift length rather than being pivotally mounted directly to the forklift""s frame in a fixed manner. Traversing boom carriages typically employed a hydraulically controlled boom carriage mounted to a pair of parallel rails that enabled the boom carriage, and thus the boom attached thereto, to traverse the rails longitudinally towards the front or rear of the forklift frame.
As is known to one of ordinary skill in the art, traversing boom carriages were employed to increase the load handling ability of a forklift. For example, delivery of a load to the second or higher floor of a building with a fixed boom-pivot required raising the boom to the necessary angle, extending the boom to the approximate desired length to positioning the load handling device adjacent to the delivery area and then performing an iterative process involving adjusting the length and height of the boom to transport the load laterally to the desired position while maintaining the load of a constant elevation. A traversing boom carriage eliminated this iterative process by allowing the forklift operator to position the load adjacent to the delivery area and simply causing the boom carriage to traverse forward to locate the load in the delivery area. The traversing carriage provided a simple manner of obtaining lateral movement of the load while maintaining it at a relatively constant elevation.
The traversing carriage of the traversing boom type forklift added a new factor to the transport configuration of forklifts. As known to those skilled in the art, the boom carriage was typically positioned at or near its rearward most position at the rear of the forklift frame for stability. However, the guide rails along which the carriage traveled, as well as the carriage itself, obstructed the forklift operator""s view of the terrain on the side of the forklift opposite the operator""s cockpit when the forklift was in the transport configuration. The outermost guide rails and the carriage became the limiting factors of operator visibility of that terrain.
It is one of the principal objectives of the present invention to provide a rough terrain forklift that provides optimum terrain visibility to an operator.
It is another objective of the present invention to provide a forklift having a boom pivotally mounted on a traversable carriage and an engine mounted between frame rails.
It is still another objective of the present invention to provide a forklift having a low overall profile and optimum terrain visibility to an operator.
It is yet another objective of the present invention to provide a forklift having a traversing boom carriage.
It is another objective of the present invention to provide a forklift having a traversing boom carriage mounted on guide rails that facilitate optimum operator visibility of the terrain surrounding the forklift.
It is an additional objective of the present invention to provide a forklift having a traversing boom carriage mounted on a pair of guide rails, one or both of which are located low on the forklift to facilitate optimum operator visibility of the terrain surrounding the forklift.
It is a further objective of the present invention to provide a forklift having a pair of boom carriage guide rails, the outer one of the guide rails being lower than the inner guide rail.
It is yet another objective of the present invention to provide a traversing boom carriage for a forklift having the outer one of a pair of legs longer than the inner one of the pair of legs to accommodate a vertical offset of a pair of corresponding guide rails on the forklift.
It is still another objective of the present invention to provide a traversing boom forklift in which the carriage is guided by a single set of guide tracks.